5 layer activate carbon filter pm2.5 protective pm2.5 mask pad fareplacement pad mask inner pad gasket replacement pads mask

5 layer protective pm2.5 mask pad fareplacement pad mask inner pad gasket replacement pads mask.1.the first layer: high efficient filter cloth filter the dust of micron.2.the second layer: meltblown cloth to filter industrial pollutants, automobile exhaust, second-hand smoke pollen allergies.3.the third layer: high efficient filter cloth filter benzene and a smaller function of filtering dust microns.4.the fourth layer: activated carbon cloth filter density, sma.